The heart of a HEIDENHAIN encoder is its measuring standard, usually in the form of a grating with typical line widths of 0.25 µm to 10 µm. These precision graduations are manufactured in a process invented by HEIDENHAIN (e.g. DIADUR or AURODUR) and are a decisive factor in the function and accuracy of encoders. The graduations consist of lines and gaps at defi ned intervals with very little deviation, forming structures with very high edge definition. These graduations are resistant to mechanical and chemical infl uences as well as to vibration and shock. They have a defi ned thermal behavior.